Plural for string in Media Library

[pavelevap]

String "Media permanently deleted." (wp-admin/upload.php:207) should be prepared for plural in localized versions. You can delete one, two or five media files at once.

[nacin]

Quick patch, but we may be getting ahead of ourselves keeping this consistent across messages for other message strings. Related, #11184. Could be 3.0.

[westi]

In my tests the $deleted var is only set when you delete a single item and then it is set to 1 for bulk deletes it is not set.

I also don't want another string change now - moving to 3.0 for now.

[nacin]

New patch. Refactors deleted, trashed, untrashed actions. I imagine more of media will change later in the 3.0 dev cycle but this is a start to bring it in line with how posts etc. are treated.

[hakre]

Related: #11515

[nacin]

(In [13153]) Improve updated messages in Media Library. Add plural strings, add Undo links for trash. Fixes #11402